Mine drove me crazy with same problem, although older 1991 Maristar. Ended up being the electronic ignition was breaking down after engine warmed up. When cooled off, boat cranked and started like a charm. Not troubleshooting your problem, just giving my experience. Good luck!!!

Hi
Ive got an X7 and I am in the UK. I cannot offer you a solution (not clever enough) but I would be really appreciative if, when you solve the problem,you let us all know what fixed it.
A PM would be really helpful as I would hate to miss it on new posts. Good Luck

When you say "it would not completely turn over", you mean the starter is turning over very slowly, somewhat like when you have an almost dead battery? It may in fact be the starter itself. Several posts on here where that was the issue. Seems a little premature for a 2004 boat, but possible I'm sure. It would cost nothing to remove starter and have it bench checked at an auto parts store.

Mine had the slow hot start condition as well. It would just barely turn over, leaving you stranded. Next time, cold start in driveway, had no issues. Several cycles like that will drive you crazy. I replaced starter with a new Arco gear reduction type and problem solved. Starters can look fine and still be bad.

Of course, you should have already checked the cables, terminal connections, ground, etc. I'll say it before someone else does, Stop throwing parts at the problem until the problem is diagnosed, especially expensive ones like ecm's and fuel pumps.

Not sure why dealer would think the ecm is bad if it is not turning over? Maybe I'm misunderstanding the issue. Does it (crank) turning over freely, just doesn't start when hot?

I apologize it I wasn't clear enough but I think the starter is fine as it is cranking. It seems like it isn't getting enough fuel to get going fully.

Check your relay switches. They are on at the back of the motor on top. Should be 3 of them. I run into the same problem a couple of years back. In and out of the water, thought it was pump, changed that and ran for a while and bam, down again....after a thorough inspection of all wires, fuses, switches, ignition blah, blah....we found it to be one of the relay switches. Pulled it apart and there was a burned spot on one of the prongs. Move it one way, boat would fire, move it another and boat would not.

relay switches are $14. keep one handy, it has happened to other boating friends of mine, and the first thing they do is replace the pump only to still have problems later.....

give it a look.

Thanks! I will check and see if that might have been the issue. My neighbor is an electrician and he said he had a similar problem with his mustang and that was the culprit

Mine drove me crazy with same problem, although older 1991 Maristar. Ended up being the electronic ignition was breaking down after engine warmed up. When cooled off, boat cranked and started like a charm. Not troubleshooting your problem, just giving my experience. Good luck!!!

Wow that's interesting. How did you finally diagnose that as the problem?
Thanks for the input

I was also there when our fellow TT member was running the diagnostics. When they tried to start it acted as if it was starving for something and there was a lot of fuel smell in the air, so we all guessed "AIR". He then 'exercised' the AIC (I think that was what he did) and it started right up. However, after running it back to the ramp and loading it up, he shut it off and tried starting it again, with no success.

It wasn't starving for air as much as it was delivering too much fuel. During cranking, the ECM is programmed to deliver fuel based on coolant temperature, barometric pressure (sent by the MAP sensor) and throttle position. If any of these is wrong, it will cause hard starting but a closed IAC will only require opening the throttle to start the engine. If the IAC is operating and it requires opening the throttle to get it to start, it's usually the ECT and if the MAP or TPS are sending bad info, it should start but it might surge, it will run like a dog, use a lot of gas and top end will suffer.